App/Databases/Overview
From XOWA: the free, open-source, offline wiki application
XOWA stores wiki data in SQLite databases. These databases can be classified as either Wikitext or HTML
SQLite
XOWA uses SQLite database files to store its data.
- Files have an extension of either ".xowa" or ".sqlite3". Note that ".xowa" files are just plain old sqlite3 databases with a renamed extension.
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Files are limited to 2 GB. Note that SQLite can easily handle files greater than 100 GB. The 2 GB limit is imposed for the following two constraints:
- 2 GB limit for SQLite files on Android. I've not found any documentation that states this, but opening a file larger than 2 GB file always fails.
- 4 GB limit for FAT32 on flash cards. FAT32 is an old file-system format. However, it is the only format that is supported natively by all major operating systems. I install a set of wikis on a 200 GB FAT32-formatted microSD card and carry it around from machine to machine
Various programs can be used to read SQLite3.
- sqlite3 command shell: This is the official shell for SQLite. Instructions are available here: the https://www.sqlite.org/cli.html . Download is available here: https://www.sqlite.org/download.html
- SQLite browser. This is a free, open-source GUI that can be useful for those who don't want just a command-line shell. See: http://sqlitebrowser.org/
XOWA Database sets: Wikitext vs HTML
There are two types of database sets for XOWA: Wikitext and HTML
Wikitext
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Wikitext is a custom language by MediaWiki to generate HTML. For example, two apostrophes are used for italics:
''italics'' -
Wikitext databases will have
-text-in the file name. For example,en.wikipedia.org-text-ns.000.xowa - Users can generates this Wikitext set by using either Dashboard/Import/Online or Dashboard/Import/Offline
- Wikitext databases have been supported since the very start of XOWA. As such, they have a full set of functionality
- However, Wikitext databases are slower. They need to take the Wikitext and convert it to HTML. As such, Wikitext databases don't work for Android, nor for other low-spec machines like Raspberry Pi
HTML
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HTML is the raw text as used by a web browser. For example, the following is used for italics:
<i>italics</i> -
HTML databases will have
-html-in the file name. For example,en.wikipedia.org-html.xowa - Users can generate this HTML database using Dev/Command-line/Thumbs. However, for most users, they will just download the already-generated HTML databases from http://archive.org through Special:XowaDownloadCentral
- HTML databases have only been supported recently (as of 2016-06). As such, they are missing a small percentage of functionality. The most significant piece of that functionality is Popups, but there may be other features.
- HTML databases are fast, as they don't need to convert Wikitext to HTML. As such, HTML databases are used for Android and recommended for Raspberry Pi